I was reading Greg's book and he mentioned about uhooking the grip in the snatch at some point. Where is that point? Is it when you are pushing under the bar? I tried to work on that today and my snatch went to shit so badly that I just stopped rather than get more pissed off than I was. I am sensative about my snatch. Anyone?

I have a similar problem. I keep the hook grip throughout the snatch. I focus on switching the grip during drills. I expect I'll eventually break the habit. However, I don't try to fix it when I snatch because I have anticipated having the same problem you are experiencing.

sometimes i feel like i crush my thumb between my fingers and the bar in the hook grip. i actually mess up my lifts sometimes because i squeeze tight and the thumb just kills. if you hold your thumb in front of your face, i feel like the bar presses one one side (right or left) and my fingers crush the other side. it feels like it's on the bone, not flesh. this tends to happen more when i stick my thumb under both my middle and index as opposed to just the index. thus i sometimes opt for the index just to avoid pain, but then my grip is not strong enough to adequately support the lift. what's up?

Releasing the hook grip was touched on on page 59.
However it goes into more detail during the description of the third pull on the bottom of page 96.
It states... "if the athlete chooses to release the hook grip in the overhead position, this must occur extremely rapidly and at the last possible moment, as the hand is finishing its final turnover from a neutral to extended wrist and the athlete begins driving up against the bar. Prior to this, the thumb and fingers will still be actively resisting the forces of the bar and the thumbs' release will cause the bar to slip."

Now keep in mind that there is no "you have to keep your hook grip". This is a personal choice. I keep my hook grip because it makes me feel more solid. Greg releases his hook grip. Play around with it and see which you prefer.

And yes, Greg does frequently say that releasing the hook grip should be taught in the very beginning, because it can be difficult to go back and start releasing it after getting used to holding it.

Gripping tightly inhibits the extension of the elbow as evidenced by proper punching technique in which the fist is not clenched until just before contact. Thus, the hook should be released just before pushing oneself under the bar. Beware, however, that this relaxing of the grip may cause the hands to move laterally during the unsupported phase. This is not a problem if you are a large lifter and are taking a collar-to-collar grip, or wish to pull with a narrower grip and catch it in a collar-to-collar. A good athlete could actually use this variation to optimize technique by pulling with a more comfortable, narrower grip and then moving the grip out during the catch to minimize the height at which the bar is supported. I believe the rule allowing this change in hand spacing was instituted in 1984 or '83.